1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member comprising a photosensitive layer containing an azo pigment having a specific structure, and to a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.
2. Related Background Art
Electrophotographic photosensitive members having organic photoconductive materials exhibit advantages in that their productivity is satisfactory, their cost can be reduced relatively and their color sensitivity can desirably be controlled by adequately selecting the pigment or dye used. Therefore, various studies of such electrophotographic photosensitive members has been carried out. In particular, an electrophotographic photosensitive member having a function-separated-type photosensitive layer has been developed in order that poor sensitivity and unsatisfactory durability as have been experienced with the conventional organic electrophotographic photosensitive member can be overcome. The foregoing function-separated-type photosensitive member has a charge generating layer which contains charge generating materials, such as an organic photoconductive pigment and dye, and a charge transporting layer which contains charge transporting materials, such as photoconductive polymers and low-molecular weight organic photoconductive materials.
Among the organic photoconductive materials, the azo pigments exhibit excellent photoconductivity and various kinds of these materials can be relatively easily obtained by combining amine components and coupler components. Therefore, various azo pigments have been disclosed, for example, in Japanese Patent Laid-Open No. 60-46561, Japanese Patent Laid-Open No. 60-131539, Japanese Patent Laid-Open No. 62-295062, Japanese Patent Laid-Open No. 1-252966 and Japanese Patent Laid-Open No. 4-96068.
In recent years, however, there have been demands for higher image quality and superior durability. To meet these demands, electrophotographic photosensitive members having higher sensitivity and superior electrophotographic characteristics, even after repeated use, have been desired.